On Bounds for the Product Irregularity Strength of Graphs. - Ratko Darda; Ademir Hujdurovic (Graphs Comb., 2015)

Searching for square-complementary graphs: non-existence results and complexity of recognition. - Ratko Darda; Martin Milanic; Miguel A. Pizaña (CoRR, 2018)

Searching for square-complementary graphs: Complexity of recognition and further nonexistence results. - Ratko Darda; Martin Milanic; Miguel A. Pizaña (Discret. Math., 2021)